Jj. Meter et al., EFFECT OF INTRAOPERATIVE BLOOD-LOSS ON THE SERUM LEVEL OF CEFAZOLIN IN PATIENTS MANAGED WITH TOTAL HIP-ARTHROPLASTY - A PROSPECTIVE CONTROLLED-STUDY, Journal of bone and joint surgery. American volume, 78A(8), 1996, pp. 1201-1205
The effect of intraoperative blood loss on serum levels of cefazolin i
n patients being managed with total hip arthroplasty was studied. Eigh
teen patients, thirteen men and five women, with a mean age of sixty-f
ive years (range, forty to eighty-five years) were enrolled in the stu
dy. Fifteen had a primary total hip arthroplasty and three, a revision
. Each patient served as his or her own control. Baseline clearance of
cefazolin was determined at a minimum of forty-eight hours before the
operation. Each patient received one gram of cefazolin intravenously.
Serial serum concentrations were determined from specimens drawn at z
ero, five, ten, twenty, thirty, sixty, 120, 240, and 300 minutes after
administration. Fifteen minutes before the skin incision was made, ea
ch patient again received one gram of cefazolin intravenously. Serum s
amples were collected at the same time-intervals, and the serum levels
of cefazolin were determined with use of capillary electrophoresis. D
ata regarding intraoperative blood loss as well as replacement of flui
d and blood were recorded. The administration of the antibiotic, retri
eval of the serum samples, and estimation of the blood loss were perfo
rmed by the same person in the same manner for all patients. The preop
erative and intraoperative creatinine clearances (mean and standard de
viation), estimated with use of the formula of Cockcroft and Gault, we
re 62.06 +/- 21.28 and 74.02 +/- 24.75 milliliters per minute, respect
ively. The amount of intraoperative blood loss averaged 1137 +/- 436 m
illiliters (range, 675 to 2437 milliliters). The preoperative and intr
aoperative cefazolin clearances averaged 0.49 +/- 0.21 and 0.52 +/- 0.
30 milliliter per minute per kilogram, respectively. During joint repl
acement, the commonly accepted interval between doses of cefazolin is
four hours. In the present study, the serum level of cefazolin at four
hours was forty-five micrograms per milliliter. This corresponds to a
n osseous concentration that well exceeds the minimum inhibitory conce
ntration for Staphylococcus aureus, which is 0.5 microgram per millili
ter. This study suggests that, with blood losses of more than 2000 mil
liliters, it is not necessary to administer cefazolin at intraoperativ
e intervals of less than four hours in order to maintain a concentrati
on of antibiotics that is higher than the minimum inhibitory concentra
tion for the most common infecting organisms.